Bruno Mars’ second studio album, Unorthodox Jukebox, is exactly that -- a surprising mix of sultry, funky, and genre-bending sounds. Fret not, fans: the pop singer’s signature retro-soul tunes about falling in love and heartbreak are still there, along with hints of reggae, old school Motown, and New Wave.

With the help of his production team The Smeezingtons, Jeff Bhasker, Mark Ronson and Diplo, Mars channels R. Kelly for the racy “Gorilla,” a tune about capping off a night of drinking in the bedroom, while the album’s lead-single, “Locked Out of Heaven,” has garnered comparisons to The Police.

Speaking to The Huffington Post, Mars says he was inspired by Amy Winehouse to experiment with diverse sounds: “I felt like everything I've been saying, everything I wanted to do, she did it… You couldn't put it in a box 'cause it could be played on rock stations, it could be played on rhythmic stations, it could be played on pop radio, and I've always wanted to make music like that -- that could be spread out, and can't be pigeon-held to one thing.”

Jason Lipshutz of Billboard commends the album’s diversity: “Unorthodox Jukebox succeeds in mixing its safer stylistic choices with its relatively bold ideas. First single ‘Locked Out Of Heaven,’ for instance, remains dizzyingly enjoyable, its 80s influences sported proudly like cub scout badges; yet all the ‘Oh, YEAH, yeahs!’ in the world couldn't make the song more than a lightweight affair. But when ‘Heaven’ is experienced alongside the uncluttered R&B of ‘Moonshine’ and dance floor sucker-punk ‘Money Make Her Smile,’ the low stakes are easy to forgive. After the success of Doo-Wops & Hooligans, Mars should be allowed to cash in with a victory lap, but Unorthodox Jukebox is proudly living up to its titular rhyme by prodding at different musical ideas. Even when Mars clumsily swings for the fences, the listener has to commend him for picking up the bat.”

Allison Stewart of Washington Post writes, “It used to be that there wasn’t much to know about Mars, except that he was very good at singing charming, edgeless, hip-hop-flavored ballads while wearing a variety of jaunty hats. His platinum-plus debut, Doo-Wops & Hooligans, earned Mars comparisons to fellow vanilla-flavored Hawaiian balladeer Jack Johnson, mostly because there didn’t seem to be much else to say about him. But a post-success arrest for cocaine possession added subtle bad-boy shadings to Mars’s image, and while Jukebox doesn’t take full advantage of the shift, it does kick the tires a little. It’s thematically darker than the breezy Hooligans, but musically it hews close to the formula established by its predecessor.”

New York Times’ Jon Caramanica hails Mars' lyrics as “succinct writing, a little talky, but extremely conscious of the borders. It could work on the radio. It could work on Broadway. It could work in a jazz club. It could work in any cabaret in town. Mr. Mars builds a sturdy skeleton. If the muscles atop it are sometimes too lean, well, that’s both Mr. Mars’s calling card and his crutch. He has a feathery tone, and while he’s deceptive with his power, he is not a powerhouse. That’s why on this album, on songs when he wants to grab attention, he emphasizes a particular style or influence.”

Emily Tan of Idolator expounds on the album's influences, “Unorthodox Jukebox (out December 11) doesn’t find Mars dodging genre labels so much as it finds him temporarily smothering himself in one before switching off to another. Working with production heavy hitters including Diplo, Mark Ronson and his crew The Smeezingtons, the songs openly pillage Bruno’s influences, but are slick and carefree enough that they sound fresh coming from him. The throughline (if there is one) would be the lyrics, which channel Keith Sweat and R. Kelly, and leave you with post-sex hair, wanting to take a cold shower.”

NPR’s Tom Moon criticizes the sultry singles, “Not everything on the new album is brilliant; in several tunes, the lyrics amount to generic sex talk, running status updates of his carnal whims and desires. At times it seems his skills as a composer might not be as fully developed as his wickedly expressive singing…” But Moon later adds, “even then, in the most X-rated moments, it's clear that Mars has crazy potential. Maybe he'll harness it differently on some project in the future, and settle into one lane on the expressway. For now, he's all over the road, and it's a pretty fun ride.”

Jody Rosen of Rolling Stone concludes by saying, “On his second album, Mars sings endlessly about sex -- wild, wind-swept, Wagner­ian sex. The smuttiest song here, ‘Gorilla,’ has a backbeat that would make Mutt Lange quake in his boots and a lyric that R. Kelly would kill to have written: ‘You're bangin' on my chest/Bang, bang/Gorilla . . . you and me, making love like gorillas.’ From another performer, the bombast might be a deal-breaker, but from Mars -- a master song-crafter and a nimble, soulful vocalist -- it is the stuff of great pop. As on his 2010 debut, Doo Wops & Hooligans, he infuses his songs with old-fashioned crooning as classily antique as his wide-brimmed fedora. But there's lots more: creamy Michael Jackson/Prince-schooled disco soul (‘Treasure’), frazzled Police-style rock reggae (‘Locked Out of Heaven’), Elton John-like balladry, Def Leppard grandiosity, dub reggae, all couched in beat-savvy modern production (Diplo, Jeff Bhasker, Mark Ronson). The result is a record that makes the competition sound sad and idea-starved by comparison.”